Sludge centrifuge with intermittent discharge



1, 1968 H. w. THYLEFORS 3,

SLUDGE CENTRIFUGE WITH INTERMITTENT DISCHARGE Filed Dec. 2, 1966 2Sheets-Sheet 1 B Y (47M fiy m M Oct. 1, 1968 H. w. THYLEFORS 3,403,349

SLUDGE CENTRIFUGE WITH INTERMITTENT DISCHARGE Filed Dec. 9, 1966 2Sheets-Sheet 2 I N VE N TOR 7zenric WI/he/m Thyle/ors B Y 6a), x/me,404%! 06 United States Patent 3,403,849 SLUDGE CENTRIFUGE WITHINTERMITTENT DISCHARGE Henric Wilhelm Thylefors, Stockholm, Sweden,assignor to Alta-Lave] AB, Tumba, Sweden, a Swedish corporation FiledDec. 9, 1966, Ser. No. 600,641 Claims priority, application Sweden, Dec.15, 1965, 1 30/65 6 Claims. (Cl. 233-20) ABSTRACT OF THE DISCLOSURESeparated sludge is discharged intermittently from the rotor of a sludgecentrifuge byv movements of a first valve located in the rotor andoperable hydraulically by opening and closing of a second valve forcontrolling the discharge of the hydraulic operating liquid; and thesecond valve, biased in the direction to close the first valve andthereby cut off the sludge discharge, is associated with electromagneticmeans for actuating it in the opposite direction.

This invention relates to sludge centrifuges of the type in whichintermittent discharge of separated sludge is efiected under control ofa first valve operable hydraulically by a liquid which, on opening of asecond valve, discrarges through an outlet of the rotor, the secondvalve being biased in the direction to close the first valve and therebyprevent discharge of sludge.

In prior centrifuges of this type, the movements of each of the twovalves are controlled hydraulically. However, such control of the secondvalve does not make it possible to control exactly the period of timeduring which the valve for discharging sludge is kept open. According tothe present invention, it is possible to attain more exact openingperiods for the sludge discharge by providing electromagnetic means foropening the second valve.

Although it is possible to provide the valve-opening electromagneticmeans on the centrifuge rotor itself and to operate such means fromstationary devices, the second valve, according to a preferredembodiment of the invention, is arranged to be actuated by one or morestationary electromagnets preferably mounted on the centrifuge frame. Inthis way, the devices for the operation of the magnets are simplified.

According to a preferred embodiment of the invention, in which thesecond valve is formed by a body surrounding the rotation shaft of thecentrifuge and located outside the rotor, the magnet or magnets surroundthe rotation shaft of the centrifuge. If only one magnet is used, it ismade annular; and if a plurality of magnets are used, they are arrangedin a uniform distribution around the shaft.

In order to prevent wearing between the centrifuge rotor and the magnet(or magnets) when the latter is stationary, an air space is providedbetween the magnet, usually its core, and the body of the second valvewhen it is in fully opened position.

The position of the sludge level in the centrifuge rotor can be sensedby known means. The sensing impulse thus otbained can be used to startan electrical timer which keeps the second valve open during a period oftime determined empirically.

The invention is described more in detail below, reference being made tothe accompanying drawings in which:

FIG. 1 is a vertical sectional view, partly in elevation, of theleft-hand half of an embodiment of the new centrifuge, and

FIGS. 2 and 3 are schematic views of different embodiments of a timerfor use with the centrifuge shown in FIG. 1.

3,403,849 Patented Oct. 1, 1968 ICC In FIG. 1, a centrifuge rotor 1 isdriven by a vertical shaft 2. In the wall of the rotor are sludgedischarge openings 3. These openings are closed by a piston valve 4movable vertically in the rotor and operated by liquid supplied througha channel 5 in the shaft 2. The operating liquid flows from the channel5 through holes 6 in the shaft and channels 7 in the rotor bottom into aspace 8 between the rotor bottom and the piston valve 4. The rotorbottom has additional channels 9 which serve to discharge the operatingliquid from the radially outermost portion of space 8. The outletopenings of the channels 9 are formed by tubular pads 10 of nylon orsimilar material and are noramlly closed by a vertically movableplate-like valve 11, which is biased in the closing direction by acoiled spring 12 concentrically surrounding the shaft 2.

A plurality of electromagnets 14 are mounted on the centrifuge frame 13and are uniformly distributed around the shaft 2. In its fully openedposition, the valve 11 abuts against a step 15 integral with the shaft2, whereby an air space is provided between the underside of the valveand the upper ends of the cores 16 of the magnets 14. In this way,wearing between the rotating valve 11 and the stationary magnet cores 16is avoided.

The winding or coil 17 of each electromagnet 14 is adapted to beenergized by a timer. As shown in FIG. 2, the coils 17 of the severalelectromagnets are represented collectively at 17a and are energizedfrom current source 18 (AC or DC) through a switch 20. The latter isclosed and opened under control of a motor-driven cam 19.

As shown in FIG. 3, a source 21 of direct current is used in a circuitwith a variable capacitor 22 which is connected in parallel to thewindings 17a. A switch 23 is adjustable in two different positions, oneof which is shown by a broken line and the other one by "a full line.

In operation, sludge-containing liquid to be separated is supplied tothe centrifuge rotor 1 from above through a pipe (not shown). The valve4 is kept closed by means of liquid which is supplied to the space 8through the channel 5. After an empirical determination or an impulsefrom a sludge-level-sensing means, the cam disk 19 (FIG. 2) is started.As it rotates through one revolution, the cam 19 keeps the switch 20closed for the period of time during which the valve 4 is to be keptopen. When the switch 20 is closed, current passes through the coils ofmagents 14 so that the valve 11 is attracted by the magnets and takesits opened position. Thus, the operating liquid in the space 8 is thrownout and the valve is opened, whereby sludge accumulated in thecentrifuge rotor is thrown out through the openings 3. At the step onthe periphery of the came 19, the switch 20 opens and the magnets 14release the valve 11, which is pressed back to closed position by thespring 12. The operating liquid from the channel 5 then refills thespace 8, the valve 4 then being reclosed.

When the timer according to FIG. 3 is used, the switch 23 takes itsbroken line position prior to a sludge discharge, whereby capacitor 22is charged by the source 21 of direct current. The capacity of thecapacitor 22 is adjusted to a charge corresponding to the period of timeduring which the valve 4 is to be kept open. When sludge is to bedischarged, the switch 23 is actuated to the position shown by the fullline. The capacitor 22 is then discharged through the magnet windings17, so that magnets 14 keep the valve 11 and consequently the valve 4open for a period of time corresponding to the amount of the chargestored in the capacitor.

I claim:

1. In a sludge centrifuge having a centrifugal rotor, the combination ofa first valve operable hydraulically to effect intermittent discharge ofseparated sludge from the rotor, the rotor having an outlet fordischarging the liquid by which the first valve is operatedhydraulically, a second valve for opening and closing said operatingliquid outlet, means biasing said second valve in a direction to closesaid outlet and hold the first valve in a position to prevent dischargeof sludge, and electromagnetic means for actuating the second valve inthe opposite direction to open said outlet and thereby actuate the firstvalve to a position for discharging separated sludge.

2. The combination according to claim 1, in which the electromagneticmeans are stationary.

3. The combination according to claim 1, comprising also a stationaryframe supporting the rotor, the electromagnetic means being mounted onthe frame.

4. The combination according to claim 1, comprising also a shaft onwhich the rotor is mounted for rotation, the second valve being locatedoutside the rotor and surrounding the shaft, the electromagnetic meanssurrounding said shaft.

5. The combination according to claim 1, in which there is an air spacebetween the electromagnetic means and the second valve when the latteris in its fully opened position.

6. The combination according to claim 1, comprising also a timeroperatively connected to' the electromagnetic means for maintaining saidsecond valve open for a predetermined period of time.

References Cited UNITED STATES PATENTS 3,134,932 5/1964 Ray 251-141 X3,189,267 6/1965 Thylefors 233-20 3,193,194 7/1965 Steinacker 233 203,237,854 3/1966 Thylefors 233-20 3,255,958 6/1966 Simon 233-203,272,430 9/1966 Thylefors 233 20 ROBERT W. JENKINS, Primary Examiner.

